allRGB is a website where you can find images where every single pixel is a unique RGB color. The images are 4096 by 4096 pixels big, so they cover every single RGB color too. Here is one scaled down version. (From Picdit)

Color of Sound is the mixing of the senses. Those affected by it hear colors, see sounds, and taste tactile sensations. When the two senses involved are sound and color, this phenomenon is no longer limited to synaesthetes: anyone, given a sound and time for contemplation, can ascribe color to that sound